functions/Get-DbaDbRoleMember.ps1

function Get-DbaDbRoleMember {
    <#
        .SYNOPSIS
            Get members of database roles for each instance(s) of SQL Server.
 
        .DESCRIPTION
            The Get-DbaDbRoleMember returns connected SMO object for database roles for each instance(s) of SQL Server.
 
        .PARAMETER SqlInstance
            SQL Server name or SMO object representing the SQL Server to connect to. This can be a collection and receive pipeline input to allow the function to be executed against multiple SQL Server instances.
 
        .PARAMETER SqlCredential
            Login to the target instance using alternate Windows or SQL Login Authentication. Accepts credential objects (Get-Credential).
 
        .PARAMETER Database
            The database(s) to process. This list is auto-populated from the server. If unspecified, all databases will be processed.
 
        .PARAMETER ExcludeDatabase
            The database(s) to exclude. This list is auto-populated from the server.
 
        .PARAMETER Role
            The role(s) to process. If unspecified, all roles will be processed.
 
        .PARAMETER ExcludeRole
            The role(s) to exclude.
 
        .PARAMETER ExcludeFixedRole
            Excludes all members of fixed roles.
 
        .PARAMETER IncludeSystemUser
            Includes system users. By default system users are not included.
 
        .PARAMETER EnableException
            By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
            This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
            Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
 
        .NOTES
            Tags: Role, Database, Security, Login
            Author: Klaas Vandenberghe (@PowerDBAKlaas)
 
            Website: https://dbatools.io
            Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
- License: MIT https://opensource.org/licenses/MIT
 
        .LINK
            https://dbatools.io/Get-DbaDbRoleMember
 
        .EXAMPLE
            PS C:\> Get-DbaDbRoleMember -SqlInstance localhost
 
            Returns all members of all database roles on the local default SQL Server instance
 
        .EXAMPLE
            PS C:\> Get-DbaDbRoleMember -SqlInstance localhost, sql2016
 
            Returns all members of all database roles on the local and sql2016 SQL Server instances
 
        .EXAMPLE
            PS C:\> $servers = Get-Content C:\servers.txt
            PS C:\> $servers | Get-DbaDbRoleMember
 
            Returns all members of all database roles for every server in C:\servers.txt
 
        .EXAMPLE
            PS C:\> Get-DbaDbRoleMember -SqlInstance localhost -Database msdb
 
            Returns non-system members of all roles in the msdb database on localhost.
 
        .EXAMPLE
            PS C:\> Get-DbaDbRoleMember -SqlInstance localhost -Database msdb -IncludeSystemUser -ExcludeFixedRole
 
            Returns all members of non-fixed roles in the msdb database on localhost.
 
        .EXAMPLE
            PS C:\> Get-DbaDbRoleMember -SqlInstance localhost -Database msdb -Role 'db_owner'
 
            Returns all members of the db_owner role in the msdb database on localhost.
    #>

    [CmdletBinding()]
    param (
        [parameter(Position = 0, Mandatory, ValueFromPipeline)]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstance[]]$SqlInstance,
        [Alias("Credential")]
        [PSCredential]$SqlCredential,
        [string[]]$Database,
        [string[]]$ExcludeDatabase,
        [string[]]$Role,
        [string[]]$ExcludeRole,
        [switch]$ExcludeFixedRole,
        [switch]$IncludeSystemUser,
        [Alias('Silent')]
        [switch]$EnableException
    )

    process {
        foreach ($instance in $SqlInstance) {
            Write-Message -Level Verbose -Message "Attempting to connect to $instance"

            try {
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $SqlCredential
            }
            catch {
                Stop-Function -Message 'Failure' -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }

            $databases = $server.Databases | Where-Object { $_.IsAccessible -eq $true }

            if (Test-Bound -Parameter 'Database') {
                $databases = $databases | Where-Object { $_.Name -in $Database }
            }

            if (Test-Bound -Parameter 'ExcludeDatabase') {
                $databases = $databases | Where-Object { $_.Name -notin $ExcludeDatabase}
            }

            foreach ($db in $databases) {
                Write-Message -Level 'Verbose' -Message "Getting Database Roles for $db on $instance"

                $dbRoles = $db.roles

                if (Test-Bound -Parameter 'Role') {
                    $dbRoles = $dbRoles | Where-Object { $_.Name -in $Role }
                }

                if (Test-Bound -Parameter 'ExcludeRole') {
                    $dbRoles = $dbRoles | Where-Object { $_.Name -notin $ExcludeRole }
                }

                if (Test-Bound -Parameter 'ExcludeFixedRole') {
                    $dbRoles = $dbRoles | Where-Object { $_.IsFixedRole -eq $false }
                }

                foreach ($dbRole in $dbRoles) {
                    Write-Message -Level 'Verbose' -Message "Getting Database Role Members for $dbRole in $db on $instance"

                    $members = $dbRole.EnumMembers()
                    foreach ($member in $members) {
                        $user = $db.Users | Where-Object { $_.Name -eq $member }

                        if (Test-Bound -Not -ParameterName 'IncludeSystemUser') {
                            $user = $user | Where-Object { $_.IsSystemObject -eq $false }
                        }

                        if ($user) {
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'ComputerName' -Value $server.ComputerName
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'InstanceName' -Value $server.ServiceName
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'SqlInstance' -Value $server.DomainInstanceName
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'Database' -Value $db.Name
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'Role' -Value $dbRole.Name
                            Add-Member -Force -InputObject $user -MemberType 'NoteProperty' -Name 'UserName' -Value $user.Name

                            Select-DefaultView -InputObject $user -Property 'ComputerName', 'InstanceName', 'SqlInstance', 'Database', 'Role', 'UserName', 'Login'
                        }
                    }
                }
            }
        }
    }
    end {
        Test-DbaDeprecation -DeprecatedOn "1.0.0" -Alias Get-DbaRoleMember
    }
}